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Designing and development of the SIGMA database and Geographic Information System (GIS)

The SIGMA relational database developed in this project provided the necessary facilities to perform correlation between the collected data, obtained from the different marine instruments. Attention was paid to the selection of the platform and the software for the database and GIS used, as well as to the shells, which were developed on top of the core of the database, to enable fast and easy storage and access of the parameters. Compatibility with the existing firmware of the partners was reached as well as transportability of the database.

The navigation data of the vessels used in the sea trials as well the position of the acoustic transmitter-receiver elements have been integrated in the SIGMA database and GIS to assure accurate estimates of the positions where investigations of the sea bed were made. The same holds for the geophysical measurements. The physical recovered sea bed parameters (from coring and acoustic analysis) have been used to represent graphically the nature of the investigated marine environments. The thematic maps derived from spatial analysis in the GIS are benefits for advanced visualization and decision-support systems, for research, monitoring and sustainable management activities of the marine ecosystems. Furthermore the structure of the SIGMA database and GIS (i.e. empty with respect to data inputs, but with the structure of the database included) could be used in future by third parties for other marine survey programs.

Designing and development of the SIGMA database and Geographic Information System (GIS):

1) The SIGMA relational database was needed for storing all non-graphic information directed by the necessary to reach the goal in the project. It implies:

i) Determining data sources (e.g.: historical data, derived from previous cruises; doctoral thesis and scientific publications;- Measured data from the estimated bottom parameters, sea trials, results from tank experiments; coring results).

ii) Identification and definition of parameters that are the most useful for sea bed identification and characterisation; their normalisation (type, format, dimensions, and interrelations of the data to be stored , and also elimination of ambiguous attribute and repeating groups of attributes, avoiding anomalies), their storage, and access.

iii) Acquisition or collection of all pertinent data relative to the test sites.

iv) Their storage and access. The SIGMA database objects such as Tables, Queries, sub-queries, forms and sub-forms, and reports, have been implemented during the development of the database in defining attributes and manipulating the attribute values in conjunction with the G.I.S. software packages, the Intergraph Modular GIS Environment (MGE). Two database management systems (DBMS) were chosen and implemented for use in this project: the Oracle relational database and the Microsoft Access database. Both software systems run on Windows NT operating systems. These software allowed easy storage and access of the historical and measured data from sea experiments. Before storing all these data in the designed SIGMA database, quality control and formatting processes were carried out. Flat file data or RDBMS files other than the selected RDMS were converted to Oracle or Microsoft Access tables.

2) The SIGMA GISOne of the major components of the SIGMA project was the development of a geographic information system (GIS) to analyse and integrate a wide range of acoustic, geophysical, geotechnical, geological, and sedimentological data related to seafloor environment in order to determine the sea bed characteristics. The surveys, conducted in selected representative areas have lead to the constitution of a well controlled database on sea bottom sediment characteristics. The system aided also in the acquisition, management, verification, analysis, synthesis, and interpretation of information produced and used in the project. The current state of the SIGMA GIS allows to implement a complete representation of the graphic information by means of the following associations:

i) Point feature when measured data are associated to a sampling point or station in space.

ii) Linear (line) feature when values are associated to a line on the x,y plane.

iii) Area or polygon feature when measured data are associated to a geographical area. These graphic elements contain at least two linkages, one linkage for the feature record (feature name and feature characteristics-feature type, and feature symbology) in the feature table and one linkage for the corresponding attribute record in the SIGMA relational database attribute table. A variety of spatial queries can be performed to explore possible relationships between the different parameters identified as having a significant effect on sea bed identification and characterisation, and to model their effects in the area of interest by selecting one or many layers interactively. An understanding of such relationship is essential for interpreting marine environmental impact. The results of these queries can then be displayed graphically as thematic maps so that one can observe the exact location of the specific sea beds. Indeed, a set of thematic maps on marine sea bed characteristics can be carried out based mainly on the above analytical operations. Thus, modelling operations of the area of interest may be carried out either directly on thematic map layers (using the class values) or indirectly on tables of attributes linked to spatial objects, or on both combinations of both maps and their attributes.

Related information

Contact

Leo VAN BIESEN, (Professor)
Tel.: +32-2-6292943
Fax: +32-2-6292850
E-mail
Record Number: 26883 / Last updated on: 2001-08-27
Information source: e-TIP
Collaboration sought: Joint venture agreement, Financial support, Further research or development support
Stage of development: Results of demonstration trials available, Preliminary design, feasibility study,
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